Sonographic manifestations of medical renal disease.

Ultrasound is usually the first imaging procedure used to evaluate the kidneys in a patient presenting with renal failure. It can allow the physician to make a specific diagnosis of bilateral hydronephrosis as the cause of the renal failure and irreversible end-stage renal disease when bilaterally small echogenic kidneys are seen. In the early stages of medical renal disease, the kidneys may appear normal. As parenchymal diseases progress, changes in the echo architecture of the renal parenchyma take place. These changes, however, are nonspecific and ultrasound-guided biopsy may be necessary to determine the exact histological cause of the patient's renal failure.